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Alternative stable states and phase shifts in coral reefs under anthropogenic stress
Citation
Fung, T and Seymour, RM and Johnson, CR, Alternative stable states and phase shifts in coral reefs under anthropogenic stress, Ecology, 92, (4) pp. 967-982. ISSN 0012-9658 (2011) [Refereed Article]
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Copyright Statement
Copyright 2011 Ecological Society of America
Abstract
Ecosystems with alternative stable states (ASS) may shift discontinuously from
one stable state to another as environmental parameters cross a threshold. Reversal can then
be difficult due to hysteresis effects. This contrasts with continuous state changes in response
to changing environmental parameters, which are less difficult to reverse. Worldwide
degradation of coral reefs, involving ‘‘phase shifts’’ from coral to algal dominance, highlights
the pressing need to determine the likelihood of discontinuous phase shifts in coral reefs, in
contrast to continuous shifts with no ASS. However, there is little evidence either for or
against the existence of ASS for coral reefs. We use dynamic models to investigate the
likelihood of continuous and discontinuous phase shifts in coral reefs subject to sustained
environmental perturbation by fishing, nutrification, and sedimentation. Our modeling results
suggest that coral reefs with or without anthropogenic stress can exhibit ASS, such that
discontinuous phase shifts can occur. We also find evidence to support the view that high
macroalgal growth rates and low grazing rates on macroalgae favor ASS in coral reefs.
Further, our results suggest that the three stressors studied, either alone or in combination, can
increase the likelihood of both continuous and discontinuous phase shifts by altering the
competitive balance between corals and algae. However, in contrast to continuous phase
shifts, we find that discontinuous shifts occur only in model coral reefs with parameter values
near the extremes of their empirically determined ranges. This suggests that continuous shifts
are more likely than discontinuous shifts in coral reefs. Our results also suggest that, for
ecosystems in general, tackling multiple human stressors simultaneously maximizes resilience
to phase shifts, ASS, and hysteresis, leading to improvements in ecosystem health and
functioning.
Item Details
Item Type: | Refereed Article |
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Keywords: | alternative stable states; anthropogenic stress; coral reef; differential equations models; fishing; hysteresis; nutrification; phase shift; sedimentation. |
Research Division: | Biological Sciences |
Research Group: | Ecology |
Research Field: | Community ecology (excl. invasive species ecology) |
Objective Division: | Environmental Management |
Objective Group: | Terrestrial systems and management |
Objective Field: | Assessment and management of terrestrial ecosystems |
UTAS Author: | Johnson, CR (Professor Craig Johnson) |
ID Code: | 76598 |
Year Published: | 2011 |
Web of Science® Times Cited: | 90 |
Deposited By: | IMAS Research and Education Centre |
Deposited On: | 2012-03-08 |
Last Modified: | 2017-10-31 |
Downloads: | 3 View Download Statistics |
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